Oracle's two major index types areBitmap indexesandB-Tree indexes. B-Tree indexes are the regular type thatOLTP systemsmake much use of, and bitmap indexes are a highly compressed index type that tends to be use
CREATE_BITMAP_AREA_SIZE是Oracle定义每个SGA中用于创建和维护位图的内存区域的一个参数,它的值默认为0MB,也就是说,在默认条件下,Oracle没有在SGA中专门分配用于位图的内存区域。如果该参数被设置为非0值,那么Oracle将会在SGA中创建一个名为“Create Bitmap”的内存区域,来储存位图;而且,Oracle会优先在该区域中创...
A method and apparatus for segmenting bitmaps in a bitmap index is provided. A segmented bitmap includes a plurality of bitmap segments that are used to indicate which records in a body of records that is associated with the segmented bitmap satisfy a particular criteria. Each bitmap segment...
(1) bit in one and only one of the bit vectors. Now we search using the bitmap index. SELECT COUNT(*) FROM T WHERE C IS NULL; ... Do this by counting the 1 bits in the NULL bit vector. The good things that we can note from this example are that the index is small (a ...
Oracle recommends that you enable automatic sizing of SQL working areas by setting PGA_AGGREGATE_TARGET instead. CREATE_BITMAP_AREA_SIZE is retained for backward compatibility. A larger value may speed up index creation. Cardinality is the number of unique values in a column in relation to the...
(2);// would return the rank of 2, which is index 1rr.contains(1000);// will return truerr.contains(7);// will return falseRoaringBitmap rror=RoaringBitmap.or(rr,rr2);// new bitmaprr.or(rr2);//in-place computationboolean equals=rror.equals(rr);// trueif(!equals)thrownewRun...
They identify long runs of 1s or 0s and they represent them with a marker word. If you have a local mix of 1s and 0, you use an uncompressed word.There are many formats in this family:Oracle's BBC (Byte-aligned Bitmap Code) is an obsolete format at this point: though it may ...
Alternative text used in place of name property for a bitmap. Data(S)(H) The actual bitmap data. File Name(O) The file name of the bitmap. The default directory for this file is\public\language\images(example forlanguageis enu for U.S. English). ...
这个方法将bitIndex位上的值由false设置为true,解释如下: 我们设置的时候很明显是在改变long数组的某一个元素的值,首先需要确定的是改变哪一个元素,其次需要使用与或操作改变这个元素,在上面的代码中,首先将bitIndex>>6,这样就确定了是修改哪一个元素的值,其次这里涉及到一个expandTo方法,我们先跳过去,直接看代码...
Bitmap index compression United States Patent 6205442 Abstract: A method and apparatus for compressing data is provided. The invention compresses an input bit stream into a compressed output bit stream. The input bit streams are byte aligned and classified. Bytes with all bits set to value zero...